Which tunic is the outermost layer of a typical blood vessel?

Which tunic is the outermost layer of a typical blood vessel?

• A. Tunica Intima
• B. Tunica Adventitia
• C. Tunica Media
• D. Tunica Externa

Answer: (B)

The outermost layer of a typical blood vessel is the tunica adventitia, also called the tunica externa. This layer is made mostly of connective tissue that anchors the vessel to surrounding tissues and provides structural support. In larger vessels it houses the vasa vasorum and nervi vasorum to supply the vessel wall itself. The other two tunics lie closer to the lumen: the tunica intima lines the inside with endothelium, and the tunica media is the middle layer of smooth muscle that controls vessel diameter. An external elastic membrane may separate the media from the adventitia in arteries, but adventitia remains the outermost layer.

The outermost layer of a typical blood vessel is the tunica adventitia, also called the tunica externa. This layer is made mostly of connective tissue that anchors the vessel to surrounding tissues and provides structural support. In larger vessels it houses the vasa vasorum and nervi vasorum to supply the vessel wall itself. The other two tunics lie closer to the lumen: the tunica intima lines the inside with endothelium, and the tunica media is the middle layer of smooth muscle that controls vessel diameter. An external elastic membrane may separate the media from the adventitia in arteries, but adventitia remains the outermost layer.